Background:
Clinical practice guidelines should be based on systematic reviews. However, it is unclear how many practice guidelines are based on systematic reviews/meta-analyses.

Objectives:
To investigate the proportion of clinical practice guidelines that form recommendations are based on systematic reviews/meta-analyses.

Methods:
We searched for WHO guidelines published in the last three years on the WHO website. Two review authors independently extracted the references for their recommendations and assessed whether these were systematic reviews/meta-analyses.

Results:
We retrieved 46 WHO guidelines including 788 recommendations, of which eight guidelines (17%) were based on 91 systematic reviews/meta-analyses (52 direct comparison meta-analyses, 21 network meta-analyses, 18 qualitative systematic reviews). The proportion of systematic reviews/meta-analyses cited in the recommendations of WHO guidelines was 12% (91/788).

Conclusions:
The number of systematic reviews/meta-analyses is increasing and their quality is improving. However, only 17% of WHO guidelines forming recommendations were based on systematic reviews/meta-analyses.

Patient or healthcare consumer involvement:
None.